1. Technical Field
The present invention relates to a nut feeding apparatus that feeds nuts which are to be welded to a work of an iron plate or the like to a resistance welding machine.
2. Description of Related Art
A nut feeding apparatus for resistance welding as described in JP 5251534 B, for example, is known as a conventional nut feeding apparatus. In this nut feeding apparatus, a nut is fed to an upper electrode of a resistance welding machine having a pair of electrodes facing up and down. The nut having been fed is held by the upper electrode and the nut held by the upper electrode is placed on a work fixed on the lower electrode. Then, the nut and the work sandwiched by the upper electrode and the lower electrode are energized, and thereby both are welded together.
The above nut feeding apparatus has the following configuration. A nut feeding chute extending substantially perpendicularly to the floor is combined with a nut feeder having an elongated shape and being arranged in an inclined manner, by communicating therewith at an intermediate position on an upper surface side thereof. Nuts successively falling through the chute then glide on an inclined path of the nut feeder. A nut which is so gliding is fitted to a pin of a nut receiver at a distal portion of the nut feeder to be caught thereby.
At this time, the nuts sometimes jump to drop out. In order to prevent this, a movable guide is arranged above the nut receiver. The nut receiver having the pin to which a nut is fitted is advanced together with the movable guide to a predetermined position below the upper electrode of the resistance welding machine. When the nut disposed at the predetermined position is moved to a pin of the upper electrode and is held by air pressure, the nut receiver retracts, and thereafter, the movable guide retracts. Then, the upper electrode goes down and the nut is welded to the work between the upper electrode and the lower electrode.
In the nut feeding apparatus as described in the above JP 5251534 B, however, the nut feeding chute which makes nuts substantially perpendicularly and successively fall down extends long in a vertical direction. In addition, the nut feeding apparatus has a complex structure for performing complex behavior which includes making nuts successively and substantially perpendicularly fall through the chute, making them glide on the inclined path, then fitting a nut to the pin of the nut receiver to be caught thereby, moving the received nut to the pin of the upper electrode, and holding it by the air pressure.
Due to such a complex structure as mentioned above, many components including at least two air cylinders are necessary, and therefore, there are problems that the production cost is high, and the size of the nut feeding apparatus is large mainly because the nut feeding chute extends long in a vertical direction.